Eyes move constantly when we think, when it might make more sense to look straight at whatever we are looking at. Now scientists are teasing apart what causes our eyes to move when we are thinking and not looking.

Past research suggests that rightward shifts, which are linked with the left hemisphere of the brain, were said to occur when a question elicited verbal thinking, while leftward shifts linked more with the right hemisphere were said to happen when a question elicited visual imagery. However, these findings are not always consistent.

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Now, researchers at Queens College in New York found that on average, people move their eyes twice as often when sifting through their long-term memory — for instance, when they are thinking about the sounds or shapes of letters, or when asked to name words that rhyme with a specific word. This pattern occurs not only when people are in face-to-face situations with others, but even when they are in the dark or have their eyes closed.

Their work suggests that the eye movements have little functional value — asking people to move their eyes does not make them remember any better, and asking them not to move their eyes does not make them remember any worse. Instead, the investigators suggest that eye movements and long-term memory may simply share circuits in areas such as the basal ganglia, cerebellum, frontal eye fields, and dorsolateral prefrontal cortex, as well as others.